A great amount of heat is often generated by the heating element such as transformer and transistor during the operation. If the heat can not be efficiently dissipated, it will cause an increased temperature of the heating element resulting in that the useful life of the heating element will be reduced.
Up to now, there are several ways for dissipating heat. for example, to separate the heating element from the housing or to use a nonconducting plate. However, such ways usually cause an increased temperature of the heating element. Later, another method has been developed, that is, to use a radiator disposed between the heating element and the housing and combined with a copper strip and a shield having a low thermal conductivity. However, it still cannot efficiently dissipate the heat generated by the heating element. Therefore, it is tried by the applicant to solve the above-described problems.